U. S. Department of Transportation
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Weather VariablesThese variables capture the weather conditions surrounding the incident. As described previously, the weather data originates from the METAR data archived by Plymouth University. It is then interpolated to represent a best approximation of the conditions at the time of the incident. Temperature(Weather Database) The temperature at the time of the incident is interpolated from the closest hourly readings. Figure 30 presents the overall distribution of temperature, the distribution by severity, and the distribution by incident type. The percentiles of the distribution, conditional on severity and incident type, are presented in Table 132 and Table 134. 
Figure – Distribution of Temperature The overall distribution is unsurprising. This data covers approximately ten years and the 50 States, the District of Columbia, and U.S. Territories; thus, the range seems reasonable. The overall distribution is skewed slightly left, but not dramatically so. The distribution by severity appears fairly similar. Category A and C incursions appear to have slightly higher median temperatures. One might anticipate that ice (and thus cold temperatures) would have a disproportionate effect on severity, but that does not seem to be the case. The distributions by severity also appear quite similar, with V/PD incidents having a slightly lower median temperature. This may be indicative of the involvement of snow removal vehicles in V/PD incidents.51 To further test these apparent differences by severity and incident type, two Kruskal-Wallis tests were performed, the results of which are presented in Table 133 and Table 135. Table – Percentiles of Temperature by Severity
Table – Kruskal-Wallis Test Results for Temperature by Severity
Table – Percentiles of Temperature by Incident Type
Table – Kruskal-Wallis Test Results for Temperature by Incident Type
Future Research
The results for severity indicate that, while jointly different, few of the categories can be declared different from each other. Categories C and D are the only two categories that can be declared different. This is partially due to the smaller sample of A and B incidents, leading to less precise estimates of their distributions. There does not seem to be a trend with severity and temperature. It is unclear how temperature alone might impact severity, but temperature may be a proxy for more specific weather phenomena, such as snow and ice. While snow and ice may impact severity, it is possible current operational practices (such as reducing traffic volume) already compensate for the increased risk of a severe incident. Further research, focusing on these particular phenomena (icy runways and snow) may disentangle the operational effects from the weather effects. Future Research
The test by incident type indicates that the three incident types are jointly different and that V/PD incidents are distinct from both OE and PD incidents (OE and PD incidents are not able to be distinguished). This supports the conclusion drawn from the distributional graph, but provides no further indication as to why V/PDs might have a different distribution of temperature. There is a broad range of factors that could influence V/PD incidents to occur at lower temperatures, including: the national geographic distribution of V/PD incidents, the prevalence of snow removal equipment in V/PD incidents, and changes in airport vehicle driver behavior due to cold weather. It is unlikely that temperature causes V/PDs; investigating factors related to cold weather that may cause V/PDs may be helpful in understanding this distribution and its policy implications. Directory: lib -> 46000 lib -> Strategic Plan South Sudan Country Office Context lib -> The World Order of Bahá’u’lláh Selected Letters lib -> 1. naclo 2015 – North American Computational Linguistics Olympiad lib -> Ieee/iee electronic Library (iel) lib -> Lnpa wg position on Porting of Telephone Numbers Used by Voip service Providers lib -> 1. naclo 2017 – North American Computational Linguistics Olympiad lib -> [0] B. Hardware [2] lib -> [1] B. Hardware [1] lib -> Chem I honors Unit 2 Notes: Numbers in Chemistry Measurement 46000 -> Measuring the effects of aborted takeoffs and landings on traffic flow at jfk Download 2.66 Mb. Share with your friends:
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